Identifying patients with diabetic nephropathy based on serum creatinine under zero truncated model

Abstract

Diabetes mellitus is a clinical syndrome characterized by hyperglycemia due to absolute or relative insufficiency of insulin in the body. Diabetic nephropathy is a generic term referring to deleterious effect on renal structure and/or function caused by diabetes mellitus.  In this paper, we estimate the probability of occurrence of diabetic nephropathy, taking serum creatinine as a marker for renal function/dysfunction. We adopted a Zero truncated binomial distribution (ZTBD) with parameters (n_i, p), where p, the probability that serum creatinine ≥ cutoff value, was unknown. Maximum likelihood and residual bootstrapping methods were used to estimate p. Retrospective data was collected from 132 patients diagnosed as diabetic as per ADA standards. Out of the available data of 132 patients, 72 patients had no diabetic renal complications with serum  creatinine  mean ± s.d as 0.9774± 0.12508 and 60 patients had certain diabetic complications with serum creatinine  mean ± s.d. as 1.6462 ±0.28827.The mean ± s.d. for duration of disease for 60 patients came out to be 15.46667± 5.54 (yrs) and median as 17.1 yrs. The two groups of patients were found to be significantly different with p<.001. The value of p̃ came out to be 0.4555397 and 0.445545 using maximum likelihood and residual bootstrapping methods respectively. It was found that 60 patients had non -zero probability of renal disease under ZTBD. From this study, it was concluded that the duration of diabetes along with elevated levels of serum creatinine defines a high risk group for the diabetic nephropathy.